1. Field of the Invention
The present invention relates to a recordable optical disc and a method of recording data on the recordable optical disc, which can improve a protection of the recorded data.
2. Description of the Related Art
There are various types of optical discs because of the diversification of formats of the CDs (Compact Discs) and the introduction of the DVD.
According to the formats of the CDs, there are a read only type CD-ROM (CD-Read Only) on which data can be read many times but cannot be written, a write once type CD-R (CD-Recordable) on which data can be read many times and can be written only once, and a CD-RW (CD Rewritable) on which data can be read many times and can be written many times. According to the formats of the DVDs, there are a read only type DVD-ROM (DVD Read Only) on which data can be read many times but cannot be written, a write once type DVD-R (DVD-Recordable) on which data can be read many times and can be written only once, a re-recordable type DVD-RW (DVD Re-recordable) on which data can be read many times and can be written for limited times, and a rewritable type DVD-RAM (DVD Rewritable) on which data can be read many times and can be written many times.
By the way, in a control data zone of the DVD-ROM, information important only for the DVD-ROM is written. In a zone, whose position is the same as this control data zone, of the DVD-RW, an unreadable emboss is formed or buried to thereby disable both of reading and writing in this zone, in order to prevent the falsification or manipulation of the data. Therefore, the control data is written on the DVD-RW, in a zone different from that of the DVD-ROM.
However, if such a probability is considered that important information, which is common for the DVD-ROM and the DVD-RW and is not desired to be falsified or manipulated, is commonly written on the DVD-ROM and the DVD-RW, it will be required or convenient to record such important information in the same zones on those discs.
It is therefore an object of the present invention to provide a recordable optical disc and a method of recording data on the recordable optical disc, which can prevent the data recorded in a predetermined zone on the recordable optical disc from being falsified.
The above object of the present invention can be achieved by a recordable optical disc provided with: a disc substrate; a record track formed on the disc substrate spirally or coaxially around a center of the disc substrate; and an emboss pit formed in a predetermined zone on the disc substrate in correlation with predetermined data, which is recorded on the record track in the predetermined zone.
According to the recordable optical disc of the present invention, since the data pattern of the predetermined data is known in advance, the emboss pit is formed in the predetermined zone in correlation with the predetermined data to be recorded in the predetermined zone. Then, the predetermined data is recorded in the predetermined zone where the emboss pit is formed. On one hand, although there exists the emboss pit in the predetermined zone, it is possible to normally write and read the predetermined data since the predetermined data is in correlation with the emboss pit. On the other hand, data other than the predetermined data cannot be normally written onto or read from the predetermined zone since such data other than the predetermined data are not in correlation with the emboss pit. Namely, even if it is attempted to falsify the predetermined data, a record mark and a record space of such data other than the predetermined data are probably influenced by the existence of the emboss pit, which most likely appears at the boundary between the record mark and the record space and which significantly drifts the signal level in the middle of the record mark and/or the record space.
In this manner, by forming the emboss pit, which is in correlation with the predetermined data, in the predetermined zone in advance, the reflection coefficient is intentionally decreased by the existence of the emboss pit. Therefore, the operation of falsifying the predetermined data is most likely failed due to the decrease of the reflection coefficient, while the predetermined data can be normally written and read against the decrease of the reflection coefficient.
In one aspect of the recordable optical disc of the present invention, the emboss pit is formed such that the emboss pit does not exist at a boundary between a record mark and a record space of the predetermined data.
According to this aspect, the emboss pit does not exist at the boundary between the record mark and the record space of the predetermined data. Namely, the length of the emboss pit along the record track is shorter than the length of the record mark or record space along the record track. Thus, the predetermined data can be normally written onto and read from the predetermined zone against the decrease of the reflection coefficient caused by the emboss pit.
In another aspect of the recordable optical disc of the present invention, the emboss pit is formed at a position where a length of a record mark of the predetermined data along the record track is equal to or longer than a predetermined length.
According to this aspect, since the emboss pit is formed at a position where the length of the record mark is equal to or longer than a predetermined length (e.g., 8 T, 4 T or the like, wherein T denotes a base clock cycle), it is possible to surely prevent the predetermined data from being falsified, by forming the emboss pit having a certain length (e.g., 4 T, 2 T or the like) which is shorter than that of the record mark but is longer than the base clock cycle.
In this aspect, a length of the emboss pit may be constant regardless of the length of the record mark.
By constructing in this manner, it is possible to easily form the emboss pit.
Alternatively in this aspect, a length of the emboss pit may be variable depending upon the length of the record mark.
By constructing in this manner, it is possible to keep a certain margin of the emboss pit with respect to the edges of the record mark, the length of which is variable. Namely, the emboss pit is made long if the record mark is long, while the emboss pit is made short if the record mark is short, so that an appropriate margin of the emboss pit is kept.
In another aspect of the recordable optical disc of the present invention, the emboss pit is formed at a position where a length of a record space of the predetermined data along the record track is equal to or longer than a predetermined length.
According to this aspect, since the emboss pit is formed at a position where the length of the record space is equal to or longer than a predetermined length (e.g., 8 T, 4 T or the like), it is possible to surely prevent the predetermined data from being falsified, by forming the emboss pit having a certain length (e.g., 4 T, 2 T or the like) which is shorter than that of the record space but is longer than the base clock cycle.
In this aspect, a length of the emboss pit may be constant regardless of the length of the record space.
By constructing in this manner, it is possible to easily form the emboss pit.
Alternatively in this aspect, a length of the emboss pit may be variable depending upon the length of the record space.
By constructing in this manner, it is possible to keep a certain margin of the emboss pit with respect to the edges of the record space, the length of which is variable. Namely, the emboss pit is made long if the record space is long, while the emboss pit is made short if the record space is short, so that an appropriate margin of the emboss pit is kept.
In another aspect of the recordable optical disc of the present invention, a plurality of emboss pits each having a structure same as the emboss pit are formed in the predetermined zone.
According to this aspect, since a plurality of emboss pits are formed in the predetermined zone, it is possible to more reliably prevent the predetermined data from being falsified.
In this aspect, a first emboss pit of the emboss pits may be formed at a position where a length of a record mark of the predetermined data along the record track is equal to or longer than a predetermined length and a second emboss pit of the emboss pits may be formed at a position where a length of a record space of the predetermined data along the record track is equal to or longer than the predetermined length
By constructing in this manner, since the first emboss pit is formed at a position where the length of the record mark is equal to or longer than a predetermined length (e.g., 8 T, 4 T or the like) and since the second emboss pit is formed at a position where the length of the record space is equal to or longer than a predetermined length (e.g., 8 T, 4 T or the like), it is possible to surely prevent the predetermined data from being falsified, by forming the emboss pit having a certain length (e.g., 4 T, 2 T or the like) which is shorter than that of the record mark or space but is longer than the base clock cycle.
Further in such a structure, a length of the first emboss pit along the record track may be variable depending upon the length of the record mark and a length of the second emboss pit along the record track may be variable depending upon the length of the record space.
By constructing in this manner, it is possible to keep certain margins of the first and second emboss pits with respect to the edges of the record mark and space respectively. Namely, the first emboss pit is made long if the record mark is long, while the first emboss pit is made short if the record mark is short, so that an appropriate margin of the first emboss pit is kept. On the other hand, the second emboss pit is made long if the record space is long, while the second emboss pit is made short if the record space is short, so that an appropriate margin of the second emboss pit is kept.
In the aspect in which a plurality of emboss pits are formed in the predetermined zone, a length of each of the emboss pits along the record track may be constant.
By constructing in this manner, it is possible to easily form the emboss pits.
In another aspect of the recordable optical disc of the present invention, the predetermined zone is in a control data zone, and the predetermined data is control data to control a recording and/or reproducing operation of data recorded on the record track in a data record zone, which is different from the predetermined zone and where the emboss pit is not formed.
According to this aspect, the control data recorded in the control data zone can be prevented from being falsified. The data such as video data, audio data or the like, in the data record zone can be recorded and/or reproduced in accordance with the control data.
In this aspect, the control data zone may be within a lead in area.
By constructing in this manner, the control data in the control data zone in the lead in area can be prevented from being falsified.
In another aspect of the recordable optical disc of the present invention, data other than the predetermined data is recorded on the record track in a data record zone, which is different from the predetermined zone and where the emboss pit is not formed.
According to this aspect, it is possible to normally record and reproduce the data in the data record zone, where the emboss pit is not formed.
In another aspect of the recordable optical disc of the present invention, the recordable optical disc is further provided with a record layer, which is formed on the disc substrate and by which data including the predetermined data is recorded on the record track.
According to this aspect, the data including the predetermined data such as control data etc., as well as video data, audio data etc., can be surely recorded on the record track by virtue of the record layer.
In this aspect, the record layer may comprise a material capable of a recording operation of write many times type.
By constructing in this manner, a write many type optical disc such as a DVD-RAM or the like can be realized.
Alternatively in this aspect, the record layer may comprise a material capable of a recording operation of write once type.
By constructing in this manner, a write once type optical disc such as a DVD-R or the like can be realized.
Further alternatively in this aspect, the record layer may comprise a material capable of a recording operation of write limited times type.
By constructing in this manner, a write many type optical disc such as a DVD-RW or the like can be realized.
In another aspect of the recordable optical disc of the present invention, the recordable optical disc is further provided with a reflective layer formed on the disc substrate for reflecting a light beam for a recording and/or reproducing operation of data recorded on the record track.
According to this aspect, the data including the predetermined data such as control data etc., as well as video data, audio data etc., can be surely recorded and/or reproduced on the record track by virtue of the reflective layer, which reflects a laser beam for a recording and/or reproducing operation.
The above object of the present invention can be also achieved by a method of recording data on the above described recordable optical disc of the present invention (including its various aspects). The method is provided with: a process of forming the emboss pit on the disc substrate; and a process of recording the predetermined data in the predetermined zone.
According to the method of the present invention, the emboss pit is formed in advance in the predetermined zone in correlation with the predetermined data to be recorded in the predetermined zone. Then, the predetermined data is recorded in the predetermined zone where the emboss pit is formed. Therefore, the operation of falsifying the predetermined data is most likely failed due to the decrease of the reflection coefficient caused by the emboss pit, while the predetermined data can be normally written and read against the decrease of the reflection coefficient caused by the emboss pit.
In one aspect of the method of the present invention, the method is further provided with a process of recording data other than the predetermined data in a data record zone, which is different from the predetermined zone and where the emboss pit is not formed.
According to this aspect, after the predetermined data is recorded in the predetermined zone such as a control zone in a lead in area, the data such as video data, audio data or the like other than the predetermined data is recorded in the data record zone, by a user at home for example. Accordingly, the data in the data record zone can be recorded and/or reproduced in accordance with the predetermined data in the predetermined zone, which is not falsified.
The nature, utility, and further features of this invention will be more clearly apparent from the following detailed description with respect to preferred embodiments of the invention when read in conjunction with the accompanying drawings briefly described below.